This research program is designed to investigate the structure and enzymatic properties of myosin in pregnant and non-pregnant uterus. The hypothesis to be investigated is the presence of "pregnancy" genes in uterus that are specifically expressed during pregnancy thus structure of myosin (and other muscle proteins) would be different in pregnant and non-pregnant uteri. Differences in myosin structure would cause differences in myosin enzymatic properties or in the regulation of actin-myosin interaction which in part should be responsible for the changes of uterine contractility properties during pregnancy. The overall objectives of this project include comparative studies of myosin in non-pregnant uterus: a) subunit structure; b) molecular weight and charge properties of the myosin light chain; c) content of methylated amino acids; d) homologous peptide isolation and sequencing of ATP-ase activities of the myosin before and after chemical modifications. BIBLIOGRAPHIC REFERENCE: Gabor Huszar: Isolation of Human Placental Myosin (Soc. for Gynecologic Investigation, Vol. 8, 59, 1977).